Join Brian Bradley for an in-depth discussion in this video Working with interactive rendering, part of SketchUp: Rendering with V-Ray 3.
- [Instructor] V-Ray Interactive, formerly known as V-Ray RT in version two of the software, is, as the name suggests, an interactive rendering engine that can be used to speed up the development of most elements in the scenes that we are producing, perhaps most notably though, in the areas of both lighting and materials. To demonstrate the ease with which we can use this tool set, let's open up the asset editor and jump into the Settings section. Right at the top, we have a rollout entitled Renderer that gives us the ability to choose the type of rendering algorithms that we want to use, so interactive, progressive, and GPU-accelerated.
To turn the interactive option on, all we need to do is flick the switch and both the interactive and progressive options become enabled. Now at this point, we can turn the interactive aspect of V-Ray off, and still be left using the production renderer in progressive mode, but you will notice that we can't have the interactive engine running and turn the progressive option off. This is because the interactive engine is actually a path-trace renderer that uses a set of algorithms designed to compute lighting in a 3D scene in a manner that is as faithful as possible to the way in which the physics of light work in the real world.
In fact, path tracing by default naturally simulates a lot of the effects that typically have to be specifically added to a render when using more conventional computing methods, effects such as soft shadows, depth of field, caustics, ambient occlusion, and so on. Now the problem of course is that all of this quality doesn't come cheaper in terms of the time that it takes to render, which is why the interactive engine can be run in either CPU or GPU mode, with GPU-based rendering offering quite significant speed increases over the CPU option.
Something else we can do here if I just turn all of the options off is invoke an interactive rendering session straight from the V-Ray for SketchUp toolbar by hitting the second of the rendering buttons, like so. Instantly, a render engages and the interactive and progressive switches are automatically turned on, although, as you can see, in CPU mode. If I grab the pan tool now and shift our camera view around, we can see that the render window interactively updates and rerenders in order to capture the change that I have just made.
If I come to the Lighting tab, I can change the color of the sunlight in the scene and watch that update and I can also come to the Materials tab and make changes here, and again, see those changes update very quickly. Of course, the downside here is that my CPU is going to be constantly running at full throttle for the duration of the interactive rendering session, which is why we may want to stop a session and engage the GPU option. The problem currently though is that this does significantly alter the look of our scene, whereas when rendering on the CPU, there is no real difference at all between the production and interactive engines.
I'm not sure whether this is a bug or just a limitation of the GPU algorithms at this moment in time. Hopefully though this is something we will see ironed out in the near future. If we are fortunate to have more than one GPU in our machine and so want to configure which one is used during an interactive rendering session, we can do that by coming to the Extensions menu and making our way to the GPU Device Selection option. One last thing we perhaps need to be aware of here and maybe something that you have already spotted is that if I just reopen our scene and take a look in the GI rollout in the asset editor, you can see that when the scene opens, it is set to use the Brute Force and Light Cache engines, but as soon as I hit the Render Interactive button, we switch over to using just Brute Force.
This is because both the Light Cache and the radiance-mapping engines are unsupported by the interactive renderer. Whether we use the GPU or CPU options for rendering then, working with an interactive rendering session does have the potential to speed up many parts of our day-to-day production work.
- Gamma handling in V-Ray 3 for SketchUp
- Working with interactive rendering
- V-Ray light types
- Working with irradiance mapping
- Rendering animations
- Working with the V-Ray camera
- Using the Materials UI
- V-Ray FX tools
- Stereoscopic 3D rendering
- Using V-Ray objects